Moving head optical scanners for stimulation of target samples and for reading of the fluorescent and reflective signal radiation that emerges from the samples are used in many experimental formats. However, many existing scanners are limited with respect to scan speed, resolution, and field size because of their numerous components and the high mass of their optical assemblies. It is desirable to increase scan speed without compromising resolution in order to scan many samples in a short period of time.
The movement of a light beam to effect scanning in most optical scanners is generally accomplished via galvanometer scanning mechanisms or rotating polygonal mirrors. These devices are best suited for small fields when the same objective is utilized for both excitation and collection or large fields when a separate light collector is used, usually a nonimaging optic. When it is beneficial to have coaxial excitation and detection, scanning of large fields is best accomplished by moving the scan head or by moving the sample. The lens is used only for single point illumination and collection along the center of the optical axis.
Existing moving head systems use either a stationary light source, such as a xenon lamp or a gas laser, in conjunction with an optical fiber to deliver the excitation light to the scan head, or a compact laser diode, if the appropriate wavelength is available. Laser diodes are generally available at wavelengths of 635 nm and greater. Both alternatives can be complex and expensive.
A wide variety of scan formats is necessary for many research and diagnostic applications. In particular, the scanning of large gels using fluorescent labels is an emerging format.
It is therefore an object of the present invention to provide a versatile optical scanner of simple, lightweight, low-cost design for rapid scanning of a sample using a moving scan head design.